Such an optical element, forming part of a display device, known as an electrowetting display, is disclosed for example in WO, 03/071347, A1. The electrowetting functionality provides a display with excellent brightness and contrast, and a relatively low power consumption compared to many other display technologies. One problem, however, with optical elements of the above mentioned kind is that the power consumption, albeit lower than for optical elements used in many other display arrangements, is still quite high for some applications, demanding a very low power consumption.